If you use Perl on Win32 then you won't have fork() nor alarm(). I find this to be a noticeable impediment. So, since you have the choice, I'd go with Unix.

Yes, Perl 5.6.0 for Win32 has fork() emulation but I found it trivial to break and can't recommend its use. Perhaps 5.6.1 will be significantly better (perhaps not).

        - tye (but my friends call me "Tye")